嗨，我是 Druid 的新手和 zookeeper并正在尝试他们的基本类型 here .
我所做的只是运行两个命令。第一个是运行zookeeper:
[root@ingester bin]# source zkServer.sh start
JMX enabled by default
Using config: /opt/zookeeper-3.4.6/bin/../conf/zoo.cfg
Starting zookeeper ... [1]+ Exit 1 nohup "$JAVA" "-Dzookeeper.log.dir=${ZOO_LOG_DIR}" "-Dzookeeper.root.logger=${ZOO_LOG4J_PROP}" -cp "$CLASSPATH" $JVMFLAGS $ZOOMAIN "$ZOOCFG" > "$_ZOO_DAEMON_OUT" 2>&1 < /dev/null
STARTED
所以动物园管理员似乎开始得很好。
第二个命令是运行 druid 的 tarball 内置的示例。这就是我遇到麻烦的地方。
1: [root@ingester druid-0.7.1.1]# source run_example_server.sh
2: This will run a stand-alone version of Druid
3: Please specify an example by its number.
4: Examples available:
5: 1 - wikipedia/wikipedia_realtime.spec - No Description
6: 2 - twitter/twitter_realtime.spec - No Description
7: [1] > 1
8:
9: Running command:
10: ++ java -Xmx512m -Duser.timezone=UTC -Dfile.encoding=UTF-8 -Ddruid.realtime.specFile=/opt/druid-0.7.1.1/examples/wikipedia/wikipedia_realtime.spec -classpath '/opt/druid-0.7.1.1/../config/realtime:/opt/druid-0.7.1.1/examples/wikipedia:/opt/druid-0.7.1.1/config/_common:/opt/druid-0.7.1.1/config/realtime:/opt/druid-0.7.1.1/lib/*' io.druid.cli.Main example realtime
11: 2015-06-15T11:53:01,737 INFO [main] io.druid.guice.PropertiesModule - Loading properties from common.runtime.properties
12: 2015-06-15T11:53:01,740 INFO [main] io.druid.guice.PropertiesModule - Loading properties from runtime.properties
13: Jun 15, 2015 11:53:01 AM org.hibernate.validator.internal.util.Version <clinit>
14: INFO: HV000001: Hibernate Validator 5.1.3.Final
15: 2015-06-15T11:53:02,202 INFO [main] io.druid.guice.JsonConfigurator - Loaded class[class io.druid.guice.ExtensionsConfig] from props[druid.extensions.] as [ExtensionsConfig{searchCurrentClassloader=true, coordinates=[io.druid.extensions:druid-examples, io.druid.extensions:druid-kafka-eight, io.druid.extensions:mysql-metadata-storage], defaultVersion='0.7.1.1', localRepository='/root/.m2/repository', remoteRepositories=[https://repo1.maven.org/maven2/, https://metamx.artifactoryonline.com/metamx/pub-libs-releases-local]}]
16: 2015-06-15T11:53:02,317 INFO [main] io.druid.initialization.Initialization - Loading extension[io.druid.extensions:druid-examples] for class[io.druid.cli.CliCommandCreator]
17: 2015-06-15T11:54:16,199 ERROR [main] io.druid.initialization.Initialization - Unable to resolve artifacts for [io.druid.extensions:druid-examples:jar:0.7.1.1 (runtime) -> [] < [ (https://repo1.maven.org/maven2/, releases+snapshots), (https://metamx.artifactoryonline.com/metamx/pub-libs-releases-local, releases+snapshots)]].
18: java.lang.NullPointerException
19: at org.eclipse.aether.internal.impl.DefaultRepositorySystem.resolveDependencies(DefaultRepositorySystem.java:361) ~[aether-impl-0.9.0.M2.jar:?]
20: at io.tesla.aether.internal.DefaultTeslaAether.resolveArtifacts(DefaultTeslaAether.java:289) ~[tesla-aether-0.0.5.jar:0.0.5]
21: at io.druid.initialization.Initialization.getClassLoaderForCoordinates(Initialization.java:214) [druid-server-0.7.1.1.jar:0.7.1.1]
22: at io.druid.initialization.Initialization.getFromExtensions(Initialization.java:141) [druid-server-0.7.1.1.jar:0.7.1.1]
23: at io.druid.cli.Main.main(Main.java:76) [druid-services-0.7.1.1.jar:0.7.1.1]
24: Exception in thread "main" java.lang.NullPointerException
25: at org.eclipse.aether.internal.impl.DefaultRepositorySystem.resolveDependencies(DefaultRepositorySystem.java:361)
26: at io.tesla.aether.internal.DefaultTeslaAether.resolveArtifacts(DefaultTeslaAether.java:289)
27: at io.druid.initialization.Initialization.getClassLoaderForCoordinates(Initialization.java:214)
28: at io.druid.initialization.Initialization.getFromExtensions(Initialization.java:141)
29: at io.druid.cli.Main.main(Main.java:76)
是否尝试在线下载某些内容，因为第 16 行显示正在加载 class[io.druid.cli.CliCommandCreator] 的扩展名[io.druid.extensions:druid-examples]。我位于公司防火墙后面，因此如果完成任何下载尝试，某些内容可能会被阻止。第 18 行还显示 NullPointerException。具体问题是什么？
我真的无法干净地运行这个例子。我也使用 Fedora 20，使用 Zookeeper 3.4.6 和 druid 0.7.1.1。
最佳答案
您在下载依赖项时似乎遇到了一些问题。您可以看一下:http://druid.io/docs/latest/operations/including-extensions.html关于将 jar 放入类路径中。
FWIW，通过在这里发布问题您将获得更快的回复:https://groups.google.com/forum/#!forum/druid-user
关于java - 在 Linux 中加载扩展时出现 NullPointerException，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/30845118/